Head Gasket

pdavey · Post by **pdavey** » Sat Oct 08, 2016 8:01 pm

So the truck is still idling rough. Haven't been able to figure out what the issue is.

- battery has tested fine
- all the fuel injectors have the same resistance (~12.5 ohms)
- throttle body is fine (replaced it with a new one and same result so old one is back on)
- intake manifold, map sensor and PCV valve have been replaced
- fuel rail pressure tested well at 58 PSI when charged and on
- unplugged and plugged back in all the harnesses and checked all the grounds
- Reloaded stock tune and started it with the same result
- Reloaded the Arrington performance tune
- checked all vacuum hoses and none of them are cracked or leaking

Any other thoughts from the group on what to test?

It is not throwing any P Codes or errors

The ABS and Brake lights are on buy don't have a tool to read that code, however wouldn't think that would have anything to do with idle.

The rough idle definitely sounds like it is a fuel air mixture issue

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Post by **Pit Slave** » Sat Oct 08, 2016 9:16 pm

Do you let it run for at least until the end of the warm up cycle? Aka cold start. Like how is it after 5 minutes of run time? The reason I ask is that there are two different mapping programs, one for warm up and one for run. Also I would put the original ignition wire and mag setup to eliminate that potential issue.

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Retired BLM Rig · Post by **Retired BLM Rig** » Sun Oct 09, 2016 12:42 am

It might be worth it to do a compression test, or at least put a vacuum gauge on it to see how the needle behaves.
If you give it some supplemental fuel (carb spray or propane) in the throttle body, does it smooth out and run perfect? That would help determine if it's a lean running condition. Also, try putting a stethoscope on each injector to see if you can hear them all clicking evenly. Do you have a scanner that reads live data (fuel trim or O2 feedback)? Just some thoughts off the top of my head.
Maybe that cam was bigger than you thought with lots of lope.

coder · Post by **coder** » Sun Oct 09, 2016 6:17 pm

x2 on the compression test, loss of compression on even one cylinder can cause rough idling/stalling at low rpms.

TrueCowboy426 · Post by **TrueCowboy426** » Mon Oct 10, 2016 8:27 pm

What does the truck run like off idle? Will it actually rev (I think auto's are limited to 4000 in N and P?) Is there anyway that you can two foot drive it and see if it will actually drive and rev under load? Do you have a heat gun that you can get the temperatures of the exhaust header at each cylinder? If you have one, get a buddy to keep the truck running and see if you can find a cold cylinder(s). I still think it is something electical, and maybe you have coil pack(s) that isn't firing. I chased a bad coil pack on my hemi swap and the only way I could find it was to find the cold cylinder. Not sure how these motors react with a dead cylinder on fuel injected, but carburated they can be down 1 cyl and you don't even hardly notice till you try to drive. Even down 2 cylinders it would idle at 800rpm relatively smooth.
Other than that, I'm back to saying the cam is out of time. Even 1 tooth off can cause weird crap/ I would try the heat gun and see if you can find a dead cylinder/coil pack first.
Another thing to try, is pull the vacuum line off the booster and see if it will stay running. My thinking on this is if the tune is way off (no way it should be) or the front O2's went bad (again no way they should have) the extra air will lean it out and maybe stay running. Pulling from my carb issues learning now lol.

Sorry for all the questions just having verbal diarhea going thru how I would diagnose it.

2010PWERWGN · Post by **2010PWERWGN** » Mon Oct 10, 2016 10:58 pm

Might check all your pushrods and make sure you didn't have one slip out from under the rocker arm. I've also had one miss the lifter yet look like it was in the hole. The pushrods can be tricky to install even with the special tools to hold them in place. I started rolling the engine over by hand with the valve cover off so I can watch each valve open and close. Also I think even one tooth off on your timing and catastrophic engine damage will occur, so your timing is probably ok.

pdavey · Post by **pdavey** » Tue Oct 11, 2016 9:07 pm

Thanks guys. Appreciate the other thoughts here. Have some more things to try this weekend.

On a side note started compression testing but had to stop with cylinder 1 as the tool wouldn't come out of the cylinder.

Turns out the o ring pushed it's way up on the tool. Need to work it out with pliers. Oh the fun.

I will get it fixed.

I did check out all injectors with a stethoscope and they all sound good.

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flattire · Post by **flattire** » Wed Oct 12, 2016 10:02 pm

Time to get back to basics.

You have already checked / replaced a lot of parts .

Compression test would be good but I would do a couple of easier things first.
Check vacuum.
Check for misfires with scan tool.
Check sensor readings with scan tool....all of them. Is there some data that doesn't make sense?
Is there a missing ground wire somewhere? ABS and brake lights on. Maybe they are a clue ?

pdavey · Post by **pdavey** » Sat Oct 15, 2016 12:57 pm

Ok I pulled most of the spark plugs and they looked good. I got to cylinder 6 and there is carbon on the spark plugs.

Thoughts on whether this could be the cause and what may be causing it?

Also pulled off the valve covers on that bank and all of the valves seem to be operating fine.

They all compress and release the same as the engine manually cranks.

Looking at the cylinder with a scope didn't show that it was wet and the plug is definitely carbon not oil.

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jswider · Post by **jswider** » Sat Oct 15, 2016 8:06 pm

Maybe the coil pack to #6 isn't working

pdavey · Post by **pdavey** » Sun Oct 16, 2016 3:15 pm

Checked the resistance and it seems good but need to check spark.

I am not getting any codes or misfires. Need to test the compression on that cylinder but it will be about a week and a half because of travel.

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TwinStick · Post by **TwinStick** » Sun Oct 16, 2016 9:09 pm

On my 88' Ford Ranger, I replaced the coil with a new Accel unit. Supposed to give much more spark. Truck failed in a week. Bad coil. Replaced with another new Accel coil. Failed in a week. Bought a Ford coil, no more problems. Lasted another 150k. What are the chances of getting 2 faulty coils ???

flattire · Post by **flattire** » Sun Oct 16, 2016 11:22 pm

My guess on the plug is no compression or no spark.

TwinStick · Post by **TwinStick** » Mon Oct 17, 2016 7:20 pm

Post by **Pit Slave** » Mon Oct 17, 2016 8:18 pm

Like I said earlier, put the original coil packs on and go from there. At least you know that set was running fine. I know it's a bitch but you want to be 100% it's not the ignition system.

I myself don't like changing a lot of components at once. I like to change one thing the try it out. This way I can be sure what's going on or in this case what's not working instead of guessing what failed.

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pdavey · Post by **pdavey** » Wed Nov 02, 2016 1:27 pm

She Breathes!

After going back to basics and deciding to check everything again I came across my rough idle issue.

When I reassembled the heads I apparently didn't seat the pushrod on cylinder 3's intake valve correctly and it wasn't opening the valve.

Put it all back together and now my truck is running. Of course life isn't that simple.

In drive it is running rough under load however I have narrowed that down to what I think is an oxygen sensor or catalytic converter problem.

Going to hopefully get that done next week and should be good to go.

I know I had checked all of the valves before I put it back together but feel a bit dumb that I didn't look at that sooner.

Oh well it is all learning. And damn have I learned a lot.

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RustyPW · Post by **RustyPW** » Wed Nov 02, 2016 6:21 pm

Hell of a learning curve.

pdavey · Post by **pdavey** » Wed Nov 02, 2016 6:24 pm

Hahahahahahaha. Yup. I never do things the easy way Russ. You know this.

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Mr.Smith · Post by **Mr.Smith** » Wed Nov 02, 2016 11:13 pm

Hell yeah! Good job figuring this one out Sir!

RustyPW · Post by **RustyPW** » Wed Nov 02, 2016 11:17 pm

pdavey wrote:Hahahahahahaha. Yup. I never do things the easy way Russ. You know this.

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Ain't that the truth.

Like changing a flat tire, that's sitting on a tree stump, facing down hill, in the rain.

pdavey · Post by **pdavey** » Thu Nov 03, 2016 1:35 am

If there was a crowning achievement I am pretty sure that takes the cake. Thanks again Russ and Mike for that assist.

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RustyPW · Post by **RustyPW** » Thu Nov 03, 2016 1:43 pm

pdavey wrote:If there was a crowning achievement I am pretty sure that takes the cake. Thanks again Russ and Mike for that assist.

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pdavey · Post by **pdavey** » Fri Nov 11, 2016 4:16 pm

She lives. The Power Wagon is working 100% now. I love the extra HP and torque.

The final problem was a problem I created after fixing the pushrod. When I put the valve cover back on I accidently switched the 5 & 7 cylinder ignition wires.

I spent the day tracing everything and found it.

Now it runs like it should.

I bought some magnaflow downpipes and cats so having those put on with new oxygen sensors. Will have the truck back tomorrow and likely retire the Challenger for the winter.

Thanks all for the support and help here. I learned a hell of a lot and am very happy to have accomplished all this.

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nts007 · Post by **nts007** » Fri Nov 11, 2016 4:21 pm

Awesome bud!!! Happy to hear that it was simple and now you can enjoy your truck once again.

cruz · Post by **cruz** » Fri Nov 11, 2016 4:25 pm

Atta' boy Peter , job well done .

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